Process of making nitro and chlor benzaldehyde.



llnirrn Sr'rns JULIUS OPPERMANN AND AUGUST FETTE, OF BlEBRIOI-I,GERMANY, ASSIGNORS TO KALLE AND COMPANY, OF SAME PLACE.

PROCESS or MAKING nlrno AND CHLOR BENZALDEHYDE.

SPEGIFZGATION forming part of Letters Patent No. 673,887, dated May 14,1901. Application filed April 19, 1898. $erial No. 6'78;1l6. (N0specimens.)

T0 (tZZ whom it inrty concern:

Be it known that we, J ULIUS OPPERMANN and AUGUST FETTE, doctors ofphilosophy, subjects of the King of Prussia, German Emperor, residing atBiebrich -on the- Rhine, Germany, haveinvented certain new and usefulImprovements in the Manufacture of Ortho-Nitro and Ortho-ChlorBenzaldehyde, of which the following is a specification.

As starting material for the manufacture of ortho-nitro-benzaldehyde,which, as it is known, serves for the production of the artificialindigo, (Imperial German Patents Nos. 19,768 and 73,377, Indigo salt,)hitherto the pure ortho-nitro-benzylchlorid was used by converting thesame into the nitro-benzaldehyde after the method protected by theImperial German Patent No. 48,722. The only process which has hithertobeen technically carried out for the production ofortho-nitrobenzylchlorid consisted in the nitration of benzylchlorid andseparation of the thereby formed isomers. The difficulties, however,under which the manufacturing process hitherto employed was alreadylaboring increased in the same manner as the utilization of theby-products, in particular of the paranitro-benzylchlorid formed inlarge quantities, became more diificult and as the demand increased forortho-nitro-benzaldehyde, or rather for the indigo salt obtained fromthe same. We have now found out a process which, starting from the cheaportho-nitrotoluol, permit-s of producing the ortho-nitrobenzaldehyde inany quantities.

I, If ortho-nitro-toluol is chlorinated at an elevated temperature, itis possible to convert a part of the same intoortho-nitro-benzylchlorid. At the same time other chlorinated productsare formed, while the rest remains as unchanged nitro-toluol. It is,however, a matter of extreme difliculty, attended with very greatlosses, to isolate from this reaction product the pureortho-nitrobenzylchlorid.

(a) If, however, the chlorinated oil liberated from acid by washing withalkaline water is heated with salts of certain inorganic or organicacids in alcoholic solution or in a suspension in water or othersuitable liquids, the ortho-nitro-benzylchlorid is transformed intocompounds having the nature of others, which afterward on cooling orafter previously distilling off the alcohol separate out mostly in solidcrystalline form. The unchanged ortho-nitro-toluol can now be eliminatedfrom the ortho-nitro-benzylether by distillation with steam or siphonedoff in so far as water, soluble others, or the salt-like nitrobenzylderivatives areconcerned. The benzyl derivatives separated in thismanner are obtained after filtering and pressingin a form, in which theycan be directly oxidized to the ortho-nitro-benzaldehyde.

Of the inorganic or organic acids, the salts of which are particularlyadapted forconverting the nitro-benzylchlorid into ether-like compounds,we mention the following ones: Acetic acid, oxalic acid, benzoic acid,phtalic acid, thiosulfuricacid, (hyposulfurous acid,) sulfocyanic acid,acetate of soda, sodium hyposulfite, sodium sulfocyanid. The conversionof these ether-like compounds into ortho-nitro-benzaldehyde is effectedaccording to the method described in the Imperial German Patent No.48,722. One can, therefore, as indicated therein, either directlyoxidize the others or saponify them first by treatment, preferably inalcoholic solution, with caustic alkalies at ordinary temperature or byboiling with alkali carbonates in aqueous or alcoholic solution, so asto obtain the nitro-benzylalcohol and subject the latter afterward tothe oxidation process.

(1)) It is, however, in the production of the ortho-nitro-benzylalcoholnot necessary to isolate the others previously. One can rather combinethe two operations, and thus directly obtain the nitro-benzylalcohol inone operation. To this end one mixes the crude chlorinated oil,previously liberated from acidfor instance, with acetate of soda, soda,and diluted alcoholand boils at the reflux-cooler until thetransformation is finished. The carrying out of this operation, however,neces sitates the presence of a salt which renders possible theformation of the intermediately obtained ether. From thenitro-benzylalcohol obtained in this manner the alcohol is firstdistilled off, then the unchanged nitrotoluol is driven off with steamand the alcohol remaining after cooling as a solid crystalline mass isfinally isolated by filtering and pressing.

(0-) Since the ethers, and in particular the nitro-benzylalcohol, aremuch more liable to be attacked by oxidizing agents than thenitro-toluol, one can also proceed in such a manner that the wholemixture obtained after the formation of the ether or aftersaponification of the etheror after directly converting into the alcoholis subjected to the oxidation. The thus-obtainedortho-nitro-benzaldehyde is then separated from the unchangednitro-toluol, for instance, by treatment with bisulfite.

11. As we have found, one obtains by chlorinating the ortho-nitro-toluolat elevated temperatures not only ortho-nitro-benzylchlorid, but alwaysalso ortho-chlor-benzyh chlorid, apart from other products formed insmall quantities. This is caused by the chlorin acting upon theortho-nitro-toluol partly by eliminating the nitro group andsubstituting it by chlorin. Subsequently the normal action of thechlorin upon the CH group takes place. Under suitable conditions it ispossible to conduct the chlorination in such a manner as to obtain theortho-chlor-benzylchlorid in larger quantities thanorthonitro-benzylchlorid.

(a) The isolation of the ortho-chlor-benzylchlorid from the chlorinatedproduct is possible, but causes great losses. One succeeds, however,easily in transforming this product without previous isolation into thevery valuable ortho-chlor-benzaldehyde. The orthochlor-benzylchlorid isalso converted into ether-like compounds by treatment wit-h the salts ofcertain organic or inorganic acids. One can now oxidize either directlythe ethers or the ortho-chlor-benzylalcohol obtained from them bysaponification, so to form the ortho-chlor-benzaldehyde. The separationof the two aldehydes, that of the ortho-nitrobenzaldehyde from theortho-chlor-benzaldehyde, is eflected without any difficulty, as thenitro-benzaldehyde is solid and can be distilled only very difficultlywith steam Whereas the ortho-chlor-benzaldehyde is liquid at an ordinarytemperature and can be very easily distilled over with steam. Themixture of the two aldehydes is therefore subjected to the distillationwith steam, which is continued until crystals of ortho-nitrobenzaldehydeappear in the liquid distilling over.

(12) The separation of the two ortho-substituted benzylalcohols can beeifected very easily. The ortho-nitro-benzylalcohol is scarcely volatilewith steam, While the orthochlor-benzylalcohol can be easily distilledover with steam. The crude chlorinated oil freed from acid by treatmentwith alkaline water is heated on the water-bath with sodium acetate andalcohol for seventy to eighty hours. By this the ortho-nitro andortho-chlor benzyl acetate are formed. The

unchanged ortho-nitro-toluol is driven off by steam. On cooling the twoethers are obtained in oily form. These ethers can now be transformedinto the corresponding alcohols either by treatment with causticalkalies in alcoholic solution at ordinary temperature or by heatingthem with water and alkali carbonates. On distillation with steam theortho-chlor-benzylalcohol is now driven over,

while the ortho-nitro-benzylalcohol remains. Theortho-chlor-benzylalcohol is soluble in water and crystallizes from anaqueous solution in white needles, melting at 72 centigrade. .Also inproducing the ortho-chlorbenzylalcohol it is not necessary to isolatethe others obtained as intermediate products. In fact it is much betterto proceed in such a manner that the washed oil is boiled at thereflux-cooler with a suitable salt-such as sodium acetate, dilutealcohol, and alkali carbonate-until the intermediately-formed ethers aresaponified. After distilling off the alcohol the benzylalcohols formedseparate in a crystalline state. The unchanged orthonitro-toluol and theortho-chlor-benzylalcohol can be driven off from theortho-nitro-benzylalcohol by distillation with steam. From the lastfractions of the aqueous distillate the ortho-chlor-benzylalcoholcrystallizes in long needles.

(0) The oxidation of the ortho-chlor-benzyl acetate or of theortho-chlor-benzylalcohol to the corresponding aldehyde is best effectedby means of nitric acid. One can, however, employ also other oxidizingagents for this purposeas, for instance, peroxid of lead.

Example: One hundred and forty-two kilos ortho-chlor-benzylalcohol areheated up with six hundred kilos sulfuric acid of about 55 Baum undergood agitation in a closed vessel, (temperature about 40 centigrade.)One hundred and twenty kilos of a mixture of nitric and sulfuric acidcontaining forty per cent. HNO are then slowly added. The beginning ofthe oxidation is seen by the appearance of red vapors escaping throughthe pipe mounted on the lid of the vessel. An excessively-hhgrhtemperature which may be caused by the reaction is best avoided bycooling now and again from out-side with cold water. As soon as theescape of nitrous gas ceases the mass is run into six hundred literscold water. The separated aldehyde is filtered off the acid liquid andtreated with soda solution in order to remove the last traces of acid.

(d) The oxidation of the chlor-benzylethers or of thechlor-benzylalcohol can also be effected before these products areseparated from the unchanged ortho-nitro-toluol, since the substitutedbenzyl derivatives are much easier attacked by oxidizing agents than thenitro-toluol.

III. After having described the properties of the products obtained bychlorinating ortho-nitro-toluol we are now going to explain alcohol isnow distilled off and afterward the l our new process for the productionof orthonitro-benzaldehyde and ortho-chlor-benzaldehyde from chlorinatedortho-nitro-toluol by giving some examples.

First. Two hundred and fifty kilos crude chlorinated oil (containing,forinstance, forty per cent. of benzylchlorid derivatives) are heated toabout centigrade with two hundred kilos crystallized sodium hyposulfiteand one hundred to two hundred kilos water until the transformation iscomplete, which is mostly the case after fifteen hours. The prodnet ofthe reaction which is then partly separated out is dissolved again byadding warm water, and the unchanged ortho-nitro-toluol is drawn off.the aqueous solution. From the latter the sodiumortho-nitro-benzylhyposulfite crystallizes out mixed with other productsof the reaction. The separal ion is completed by adding common salt. Theso-obtained crude product can be purified after filtering and pressingby fractional crystallization.

Second. Six hundred kilos chlorinated oil, containing about forty percent. of benzylchlorid derivatives, are boiled at the refluxcooler witheight hundred liters dilute alcohol, two hundred and fifty kiloscrystallized sodium acetate, and ninety kilos soda ash until theintermediately-formed ortho-nitro and ortho -chlor benzyl acetate aresaponified. The alcohol is now distilled 0%. On cooling a mixture of thecorresponding substituted alcohols crystallizes out from the reactionmass. It is, however, not necessary to wait for this. After distillingoff the alcohol the ortho-nitro-toluol is distilled over with steam. Theresidue is diluted with Water, if necessary, in order to keep the salts(sodium acetate, sodium chlorid, &c.) in solution. After cooling thebenzylalcohol derivatives turn solid and are filtered off and pressed.One hundred and thirty kilos of the press-cake are dissolved in fourhundred to five hundred kilos sulfuric acid of 50 to 60 Baum at atemperature of about 40 centigrade. Seventy to eighty kilos of a mixtureof sulfuric and nitric acid, containing thirty-eight to thirty-nine percent. HNO or a corresponding quantity of nitric acid or niter, are nowadded slowly. The beginning of the oxidation can be seen by the escapeof nitrous gas, and the end of the same by the ceasing of this escape.The temperature is best kept at 40 centigrade as long as the oxidationlasts, and for this purpose one cools, if necessary, with water. Afterthe oxidation is finished the mass is run into five hundred liters ofcold water. After letting the mixture rest for a while the aldehydes areseparated from the acid and the last traces of acid are removed bywashing with soda solution. The remaining mixture of the two aldehydesis then filtered and pressed. From. the pressed-off oil one obtains theortho-chlor-benzaldehyde by fractional distillation with steam. Thepresscakes consist of ortho-nitro-benzaldehyde which is sufficientlypure for technical purposes. They can, however, be purified by treatmentwith bisulfite and by distillation with steam in order to remove thelast traces of ortho-chlor-benzaldehyde.

Third. Six hundred kilos chlorinated oil (containing about forty percent. of benzylchlorid derivatives) are boiled at the refluxcooler witheight hundred liters dilute alcohol, two hundred and fifty kiloscrystallized sodium acetate, and ninety kilos soda ash until theintermediately-formed ortho-nitro and ortho-chlor-benzyl acetates aresaponified. The alcohol is now distilled off. In order to keep the salts(sodium acetate, sodium chlorid, the.) in solution, some water is added.The oily mixture, containing ortho nitrotoluol,ortho-nitro-benzylalcoh0l, and orthochlor-benzylalcohol, is separatedfrom the aqueoussalt solution and directly oxidized. For this purpose itis mixed with five hundred to six hundred kilos sulfuric acid of 50 to60Baum and oxidized under good agitation at 40 centigrade in the mannerdescribed in Example 2. The oxidized mass is run into six hundred literscold water. The oil is separated from the acid and washed with sodasolution. In order to separate the aldehydes from theortho-nitro-toluol, the oil is now mixed at a temperature of 30 to 40centigrade with dilute hisulfite solution. The undissolvedortho-nitro-toluol is separated from the aldehyde-bisulfite solution,and the latter is decomposed by adding an equivalent amount ofcaustic-soda lye. The precipitated aldehydes are filtered off andpressed. The ortho-nitro-benzaldehyde is contained in the press-cakes,the ortho-chlor-benzaldehyde in the pressed-off oil. One can alsoseparate the two aldehydes by distillation with steam. The distillationis continued until one observes that the solid orthonitro-benzaldehydebegins to distil over. In this case the orthochlor-benzaldehyde iscontained in the distillate,while the ortho-nitro-benzaldehyde remainsin the residue.

The by-products formed in small quantities besides the ortho-nitro andortho-chlorbenzylchlorid in the chlorinating process do not impair thedescribed process in any way.

In the English Patent No. 22,041 of 1896 also a process for producingortho-nitro-benzaldehyde from such a chlorinated product is describedwhich contains besides unchanged ortho-nitro-toluol only ortho nitrobenzylchlorid. The process is carried out as follows: The chlorinatedproduct is treaded with primary amins or amidosulfo-acids. In thismanner the amids or amidosulfo-acids of the ortho-nitro-benzyl areobtained. These are separated from the unchanged ortho-nitrotoluoleither by distillation with steam or, in so far as amidosulfo-acids ofthe ortho-nitrobenzyl come into question, by the solubility of theseproducts in water. This mode of separation can also be applied withadvantage to the ortho-chlorinated benzylchlorid.

Now what we claim is 1. As a new process, the manufacture of a IIOmixture of ortho-vnitro and ortho-chlor benzaldehyde from chlorinatedortho-nitro-toluol, and the separation of the two aldehydes from eachother, by boiling chlorinated ortho-nitrotoluol, previously freed fromacid with dilute alcohol, sodium acetate and sodium carbonate,distilling off the alcohol, oxidizing the remaining oil, afterseparating it from the salt solution, by a suitable treatment with amixture of sulfuric and nitric acid, thereby transforming it into amixture of ortho-nitrotoluol and ortho-nitro and ortho-chlorbenzaldehyde and separating the aldehydes from the ortho-nitro-toluol bymeans of an alkali bisulfite, liberating them from the bisulfitesolution by addition of a caustic alkali and separating the twoaldehydes from each other by pressing or distillation with steam,substantially as described.

2. As a new process, the manufacture of a mixture of ortho-nitro andorthochlor benzaldehyde from chlorinated ortho-nitro-toluol and theseparation of the two aldehydes from each other by boiling chlorinatedortho-nitrotoluol, previously freed from acid with dilute alcohol,sodium acetate and sodium carbonate, distilling off the alcohol,separating the oil from the salt solution and treating the oil soobtained with a current of steam, thereby driving over theortho-nitro-toluol, oxidizing the remaining mixture of ortho-nitro andortho-chlor-benzyl alcohol, and separating the two aldehydes from eachother, substantially as described.

3. As a new process, the manufacture of a mixture of ortho-nitro andortho-chlor benzaldehyde from chlorinated orthomitro-toluol and theseparation of the two aldehydes from each other by boiling chlorinatedortho-nitrotoluol, previously freed from acid with dilute alcohol,sodium acetate and sodium carbonate, distilling off the alcohol,separating the oil from the salt solution, then treating the oil soobtained with a current of steam, until not only the ortho-nitro-tolnolbut also the ortho-chlor-benzyl alcohol is driven over, and transformingthe two alcohols separated in this manner into the aldehydes,substantially as described.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

JULIUS OPPERMANN. AUGUST FETTE.

